Circuit breakers are developed in various installation sizes. An installation size is composed in this case of device variants having a rated current series to be established expediently. With an increasing rated current of a device, its power loss increases in a very disproportionate manner. The device variant with the highest rated current with a given installation size is determined such that for precisely this current, the power loss with a given housing volume is still without disadvantageous consequences in terms of the requirements of the switching device through its service life. If still higher rated currents are required, a larger design is developed. From the customer's point of view, it is however desirable to drive the maximum rated current within an installation size still further upwards. In order to achieve this, measures must be taken to configure the transport of heat from the housing volume in a technically more efficient manner.
There are in principle two possibilities in terms of dealing with high temperatures within a protective housing on account of unavoidable electrical power losses. On the one hand, all materials can be optimized to such a degree that they also fulfill their functional requirements at a high temperature level. This is nevertheless often not a cost-effective solution. The other procedure consists in forcing the removal of the generated heat from the housing by way of technical measures. Active cooling measures by means of housing ventilators, heat pipe arrangements or even coolant circuits form the prior art for electronic products. In order to be able to dissipate large locally generated heat quantities, this heat is distributed onto large surfaces by way of cooling elements. In this way the cooling elements are thermally bound to the components with a high electrical power loss, but are electrically insulated therefrom. Completely passively cooled systems are constructed here such that there can be a direct ambient air flow onto the required cooling elements.
The disadvantage of the prior art is that the previous heat extraction elements could not be disposed in the optimum space-saving arrangement in the switching device.